The background of the invention relates to various problems associated with known plugs for setting in pipes. Such plugs are readily used for pressure testing of pipes or weld joints therein.
The plug activation force required for setting of sealing elements and/or gripping elements for such plugs, is usually supplied by virtue of mechanical, hydraulic or pneumatic means.
A substantial problem with mechanical activation is that much of the supplied activation energy, for example a torque, is lost due to friction between movable parts in the plug. Moreover, a foothold (counteracting support) oftentimes must be taken in a suitable element in the surroundings of the plug in order to be able to supply said torque to the plug, but also to be able to prevent the plug from rotating when the torque is supplied.
Hydraulic/pneumatic activation by means of a pressurized fluid, however, is more sensitive to pressure leakages in the plug or in the transmission of pressurized fluid to the plug.
Such known plugs are associated with problems both in terms of operation, time, cost and safety.